A reader is used to measure a reflected optical spectrum from objects. In order to produce a strong reflected signal, a bright incident light is used. This poses a problem when a portable reader is desired because the power requirements (e.g., those due to the powering of the bright incident light) of the reader's operations must be satisfied using a battery. In addition, the portable reader typically needs to operate for a minimum time (e.g., 8 hours of operation) and still meet portability requirements (e.g., a maximum weight), which set limits on the amount of power that the bright incident light can consume.